The size and thickness of portable wireless communication apparatuses, such as mobile phones, have been rapidly reduced. In addition, the portable wireless communication apparatuses have been transformed from apparatuses to be used only as conventional telephones, to data terminals for transmitting and receiving electronic mails and for browsing web pages of WWW (World Wide Web), etc. Further, since the amount of information to be handled has increased from that of conventional audio and text information to that of pictures and videos, a further improvement in communication quality is required. In such circumstances, some steerable antenna apparatuses have been proposed.
Patent Literature 1 discloses an antenna device including a rectangular conductive substrate, and a planar antenna over a dielectric on the substrate. The antenna device is characterized in that a current flows in one diagonal direction on the substrate by exciting the antenna in a direction, and another current flows in the other diagonal direction on the substrate by exciting the antenna in a different direction. Thus, the antenna device of Patent Literature 1 can change its directional pattern and direction of polarization by changing the direction of a current flowing on the substrate.
Patent Literature 2 discloses a flip-type portable wireless apparatus with a open/close mechanism in which first and second housings are connected via a hinge, the portable wireless apparatus includes: a first planar conductor disposed on a first surface of the first housing along a longitudinal direction of the first housing; second and third planar conductors disposed on a second surface of the first housing opposing to the first surface, along the longitudinal direction of the first housing; and feeding means for feeding the first planar conductor and for selectively feeding the second or third planar conductor with a different phase than that used to feed the first planar conductor. The portable wireless apparatus of Patent Literature 2 can switch between the second and third planar conductors in response to a reduction in reception level, thus improving communication performance.
Patent Literature 3 discloses a portable radio unit including a dipole antenna; and two feeder means each connected to one of two antenna elements composing the dipole antenna.
Patent Literatures 4 and 5 disclose antenna apparatuses including first and second feed points respectively provided at positions on an antenna element, the antenna element being simultaneously excited through the first and second feed points so as to simultaneously operate as first and second antenna portions respectively associated with the first and second feed points, the antenna element further including electromagnetic coupling adjustment means provided between the first and second feed points for producing isolation between the first and second feed points. The antenna apparatuses of Patent Literatures 4 and 5 can simultaneously transmit and/or receive a plurality of radio signals with low correlation to each other, while having a simple configuration.